Add "scheduled_for_deletion" field to StockItem

- If set to True, this StockItem will be deleted (soon) by the background worker
- As deletion takes significant time, this prevents delete operations from blocking the UI

InvenTree/stock/models.py

@@ -209,7 +209,8 @@ class StockItem(MPTTModel):
         belongs_to=None,
         customer=None,
         is_building=False,
-        status__in=StockStatus.AVAILABLE_CODES
+        status__in=StockStatus.AVAILABLE_CODES,
+        scheduled_for_deletion=False,
     )
 
     # A query filter which can be used to filter StockItem objects which have expired
@@ -588,6 +589,12 @@ class StockItem(MPTTModel):
                               help_text=_('Select Owner'),
                               related_name='stock_items')
 
+    scheduled_for_deletion = models.BooleanField(
+        default=False,
+        verbose_name=_('Scheduled for deletion'),
+        help_text=_('This StockItem will be deleted by the background worker'),
+    )
+
     def is_stale(self):
         """
         Returns True if this Stock item is "stale".